1. Field of the Invention
This invention relates to manholes for sewer and other systems and more particularly, to a substantially watertight manhole insert and tether apparatus which is designed to seal the manhole immediately beneath a manhole cover and prevent flooding of the systems. In a preferred embodiment of the invention the manhole insert is characterized by a stainless steel, cylindrical, pan-shaped insert body having a rounded, ribbed or flat insert bottom provided with one or more pressure relief valves and connected to a tether system for securing the insert body in the manhole. The insert body has upward-standing, sloping or perpendicular sides extending from the insert bottom and terminated by an outwardly-projecting rim adapted for seating on a shoulder formed in the manhole beneath the manhole cover. The outwardly-extending rim may be seated directly on the manhole shoulder or on a seal to minimize the flow of water, sediment and contaminants from ground level around the manhole cover and through the manhole, into the sewer systems. The insert bottom receives one end of the tether through a rubber grommet extending through an opening in the insert bottom and the opposite end of the tether is extended through a pair of tether mount loops secured in the manhole wall beneath the manhole insert and terminates in fixed attachment to a keyhole clip bolted or otherwise secured to the insert bottom and spaced from the rubber grommet. Both ends of a lift strap or straps may be attached to the insert bottom opposite or adjacent to the tether, or both, typically by means of the keyhole clip mount bolt, to facilitate lifting and removing the manhole insert from a mounted position in the manhole, throughout the length of the tether. In a preferred embodiment of the invention the tether is secured in the manhole insert by a lever-type locking device as follows. The tether is threaded through a tether opening provided in one end of an elongated, U-shaped lever bar receptacle and through a registering, transversely-offset tether opening included in one end of a rectangular lever bar extending angularly or perpendicularly from the lever bar receptacle. The lever bar receptacle and lever bar together constitute a locking device for securing the manhole insert in the manhole, as described in my copending application Ser. No. 08/329,064, filed Oct. 20, 1994. After the manhole insert has been placed in the manhole, the tether is tightened through the spaced-apart tether mount loops and pulled upwardly through the rubber grommet provided in the insert bottom and the locking device is slipped along the tether to the grommet and subsequently locked onto the tether to securely seat the insert body of the manhole insert uniformly against the manhole shoulder. Locking of the locking device on the tether is accomplished as the lever bar is pivoted to lie entirely in the lever bar receptacle and the tether opening provided in the lever bar is shifted in a camming increment to misalign with the tether openings provided in the lever bar receptacle, thus crimping the tether and preventing the tether from slipping through the grommet. The hasp of a padlock is then extended through registering lock openings provided in the lever bar receptacle and lever bar and the padlock locked, to prevent reverse manipulation of the lever bar, access to the manhole and/or theft of the manhole insert. Since the tether is effectively then connected to the manhole insert at two spaced-apart points and the tether extends through the two, preferably diametrically-opposed, tether mount loops fixed in the manhole wall, the manhole insert cannot be tipped or removed from the manhole shoulder. The pressure relief valve installed in the insert bottom is designed to relieve pressure which may be generated in the sewerage system served by the manhole and also operates to relieve any vacuum which may develop in the sewer system.
One of the problems which is associated with sewer systems is that of flooding during periods of high water due to prolonged or heavy rainfall. This problem is intensified in both urban and surburban areas where increased construction activity has resulted in large quantities of concrete being poured to construct parking lots, as well as foundations and other structures. This proliferation of non-permeable construction material reduces the amount of surface area which is available to absorb rainfall and increases the flow of water in storm drains and sewer systems, as well as diversion canals, natural streams and other channels which must accept and dispose of the increased flow of water. These conditions of urban and suburban development result in flooding under circumstances where the water run-off exceeds the capacity of the storm drain and sewer systems, which are sized to receive a specified average flow of water. Moreover, although it is customary to provide separate drainage systems for rainwater and sewage, flooding of the sewerage systems by rainwater runoff sometimes creates a contamination problem.
Another problem relating to sewer and other systems is the unauthorized entry of these subterranean tunnels by children and adults for various purposes. Sewer lines and tunnels may contain toxic and/or flammable gases, low oxygen, liquid contaminants and like hazards. Furthermore, sudden rainstorms can quickly flood sewerage systems and due to the extensive network of pipes, channels and tunnels in such a system, people can easily become lost in the underground labyrinth.
2. Description of the Prior Art
Various types of closures and covers, many of which are fitted with ventilating means, have been long known in the art. An early German Patent No. 41,210 details a manhole having a removable cover connected to the manhole by a chain. Another early patent which details such a closure is the "Ventilating Vault Cover", detailed in U.S. Pat. No. 606,554, dated Jun. 28, 1898, to J. Jacobs. The ventilating vault cover is designed to close a vault opening in a watertight manner when in a closed position and vent the vault when in open configuration. U.S. Pat. No. 1,959,171, dated May 15, 1934, to N. C. Mayer shows a manhole construction which includes an adapter for raising a manhole cover after road construction. U.S. Pat. No. 3,046,853, dated Jul. 31, 1962, to C. Legendre, discloses a "Manhole Closure". The manhole closure includes a lid of one-piece construction which cooperates with a seat or manhole frame, also of one-piece construction, such that the two parts can be easily assembled for mounting in a manhole. A "Safety Replacement Cover for Catch Basins" is detailed in U.S. Pat. No. 2,576,353, dated Nov. 27, 1951, to O. W. Nelson. The cover detailed in this patent includes a dish-like, reticulate tray which is designed to provide adequate drainage into a catch basin and facilitates safety to prevent injury from stepping into the catch basin. A "Manhole Cover" is covered in U.S. Pat. No. 3,920,347, dated Nov. 18, 1975, to John T. Sauriol, et al. The manhole cover is constructed of a molded synthetic polymeric material and has a transversely intersecting structural rib network which is integrally joined with a top surface portion and encloses annular peripheral portions of the cover. The structural rib network is preferably dome-shaped, with the principal structural support disposed centrally of the cover at the apex of the dome. A "Drain Hole Seal With Bottom Bleeder" is detailed in U.S. Pat. No. 4,649,674, dated Mar. 17, 1987, to Craig S. Gaul, et al. The patent details a seal structure having a bottom bleeding feature such as a bottom bore and fitted with a flange to facilitate sealing engagement between a cover and a frame located around an access opening of the manhole. The structure includes a central portion which is downwardly depressed to avoid a path of spin of the cover. A "Watertight Manhole Insert" is set forth in U.S. Pat. No. 4,650,365, dated Mar. 17, 1987, to Franklin D. Runnels. The manhole insert is designed to prevent rainwater from entering a sanitary sewer system through manholes which are closed by manhole covers. The insert includes a shallow, dish-shaped body portion and a mounting flange designed to rest upon the supporting flange of a manhole frame. A recess is formed in the bottom of the body portion and includes a valve for releasing any pressure which may accumulate in the manhole beneath the insert. The valve is shielded to prevent damage by a manhole cover sliding across the insert. Additionally, the valve can be used as a handle to remove the insert from the manhole. The Runnels insert has also been modified in application to include a circumferential rib near the rim for stiffening purposes. A "Manhole Closure Assembly", detailed in U.S. Pat. No. 4,067,659, dated Jan. 10, 1978, and a "Manhole Closure Assembly with Valve Relief Means" covered by U.S. Pat. No. 3,712,089, dated Jan. 23, 1973, are both issued to Samuel A. Campagna, Jr., et al. Both assemblies are designed to prevent accumulated storm water from entering a manhole opening and includes a cover section having a downwardly-depressed central portion. A circular mounting flange extends outwardly from the depressed central portion and the flange is adapted to rest upon inwardly-directed manhole cover supporting flanges of the annular manhole frame. The cover section is depressed, such that the cover exceeds the path of spin when resting upon the supporting flange of the manhole frame. A valve is secured to the cover section for the purpose of relieving pressure inside the manhole when the sewer pressure exceeds a predetermined level. My U.S. Pat. No. 4,919,564, issued Apr. 24, 1990, details a "Manhole Insert" characterized by a dish-shaped seal or stopper positioned below a manhole cover to plug the manhole and prevent flooding of the underlying sewer system. My U.S. Pat. No. 4,957,389, issued Sep. 18, 1990, covers a "Method And Apparatus for Sealing Manholes", using a donut-shaped seal structure in the chimney. Other patents which detail locking devices and restraints for securing lids and cables, include the following: U.S. Pat. No. 374,458, to J. P. Davis; U.S. Pat. No. 1,384,712, to F. Shanley; U.S. Pat. No. 5,070,712, to D. Fox; U.S. Pat. No. 3,490,177, to D. C. Perrion; U.S. Pat. No. 4,101,154 to Kagstrom; U.S. Pat. No. 4,171,851, to C. Scruggs; U.S. Pat. No. 5,328,291 to R. S. Wisniewski; and U.S. Pat. No. 5,197,307 to M. L. Abbott.
It is an object of this invention to provide a new and improved manhole insert and restraint or tether which is designed to close and substantially seal a manhole and prevent rainwater from flooding a sewer or other system communicating with the manhole, as well as secure the manhole insert in the manhole or within the length of the tether, to prevent unauthorized entry into the manhole and/or theft of the manhole insert.
Another object of the invention is to provide a manhole insert and tether apparatus, which manhole insert is molded, stamped or otherwise shaped from a selected metal or synthetic polymeric material into a pan-shaped, rounded, ribbed or flat-bottomed, flanged insert body for removable installation on a shoulder provided in a manhole beneath the manhole cover in order to prevent, or at least reduce, the flow of rainwater into the manhole and the underlying disposal system and prevent, or at least minimize, theft of the manhole insert and/or unauthorized entry of the manhole, by operation of the tether.
A still further object of this invention is to provide a stainless steel manhole insert characterized by a pan-shaped insert body having a rounded, ribbed or flat insert bottom and a bottom opening which slidably receives one end of a flexible, braided or stranded stainless steel tether, the opposite end of which tether is threaded through at least two tether mount loops fixedly spaced-apart in the manhole and is then bolted or otherwise fixed to the insert bottom at a point spaced from the bottom opening. A continuous side wall extends from the manhole insert bottom, with a flange or rim outwardly-extending from the side wall, which rim engages the shoulder of the manhole located beneath the manhole cover to retard water from flowing into the manhole and the underlying sewer or drainage system, while the tether drastically reduces the incidence of theft of the manhole insert and unauthorized tipping and entry into the manhole.
Yet another object of the invention is to provide a manhole insert and slidably connecting restraint or tether apparatus and a crimp or cam lock for retarding the flow of water into a sewer or other system through a manhole and substantially preventing access into the manhole and theft of the manhole insert. The manhole insert is characterized by a rounded, ribbed or flat-bottomed closure or insert body having an outwardly-projecting flange or rim optionally fitted with a rubber seal and further including one or more lift straps or handles attached to the dish-shaped closure or insert body, which manhole insert is located in the manhole beneath the manhole cover. The tether apparatus is bolted or otherwise fixed to a first selected point on the manhole insert, extends through spaced tether mount loops, preferably spaced across the diameter of the manhole and fixed to the manhole wall beneath the manhole insert and then through an opening in the manhole insert, where it can be locked to stabilize and secure the manhole insert in the manhole.
Still another object of this invention is to provide a new and improved manhole insert which includes a pan-shaped, rounded, ribbed or flat-bottomed stainless steel stopper, plug or insert body having one or more pressure relief valves mounted therein and further including an outwardly-extending rim fitted with a rubber seal and a flexible, braided or stranded stainless steel wire tether having one end extending through a grommet in the flat insert bottom of the insert body and fitted with a lever-operated, cam-type locking device, with the opposite end of the tether extending through a pair of tether mount loops attached to diametrically opposite points in the cylindrical manhole beneath the manhole insert and fixed to a point on the manhole insert which is spaced from the grommet. One or two lift straps are mounted on the manhole insert for removing the insert body from a manhole located beneath the manhole cover and a warning tag may be attached to at least one of the lift straps, as deemed necessary.
Another object of the invention is to provide a new and improved manhole insert characterized by a stainless steel, rounded, ribbed or flat-bottomed insert body which is fitted with a flared or perpendicular side and a flange or rim for mounting in the upper portion of a manhole beneath the manhole cover. Further included is a flexible stainless steel tether having one end attached to a keyhole clip bolted or otherwise fixed to the insert body and the opposite end extending through a pair of flexible tether mount loops mounted in the manhole wall across the diameter of the manhole, and further projecting through a grommet mounted in the insert bottom element of the insert body, which grommet is spaced from the keyhole clip. The opposite end of the tether then projects through a tether opening provided in one end of an elongated, U-shaped lever bar receptacle and through a registering, transversely-offset opening included in a rectangular lever bar accommodated in and extending angularly or perpendicularly from the lever bar receptacle, which lever bar is pivoted in a camming action to rest entirely in the lever bar receptacle, crimp the tether and thus prevent the tether from slipping through the grommet. A padlock may then be secured to the lever bar and lever bar receptacle to secure the manhole insert in the manhole, in order to reduce or prevent the flow of water into an underlying sewer system, control manhole odor, prevent the accumulation of dirt and trash in the manhole and the underlying sewer and substantially prevent theft of the manhole insert and unauthorized tipping of the manhole insert to gain access to the manhole.
A still further object of this invention is to provide a method of locking a manhole insert in a manhole beneath a manhole cover, which method includes the steps of seating a manhole insert in the manhole; providing an opening in the manhole insert body; extending a flexible tether through the opening and through a pair of tether mount loops fixed to the manhole wall and securing one end of the flexible tether to the manhole insert; and sliding a tether lock on the opposite end of the flexible tether in the manhole insert, such that the manhole insert is secured in the manhole opening responsive to tightening the flexible tether through the mount loops, pulling the flexible tether through the opening to tighten the flexible tether at two points between the insert body and the manhole, sliding the tether lock on the flexible tether to the insert body and locking the tether lock on the flexible tether. The tether lock may be further secured in place by a lock such as a padlock.